Bought foster 223 go and no-go gauages and was surprised that my colt barrel/bolts will chamber the no-go.  

Is this normal?  Should I be using a field
gauge? I've never had problems with colt barrels.  Recommendations please.

In all actuality yes you should stick to the "Field" gauge. I had the same result using Forster gauges. They are comercial 223 gauges and are slightly different in comparison to the 5.56 chamber your Colts have. All Colt prebans, with a slight few exceptions, are constructed with military barrels or chambers. It was easier for Colt to standardize on this part of the weapon.

Military chambers are a bit looser because they are technicly Machine Gun chambers and need room to allow for heat expansion and ease of extraction. Most of my Colt barrels, both new and used will close on the Field gauge, barely in most instances, but still they do it. Nothing wrong there so don't worry.

Now if you get a "Maximum Field" gauge in 5.56 like the military armorers use, and it closes on it, you might need to start worrying. Even then there is room for debate.

Tony Rumore has purposely used barrels with excessive head space to induce a head space failure and he reports no problems. The man knows his stuff. I tend to be wary and not chance my prebans with operating out of specifications. But thats my choice. A good habit is to check your weapons with the field gauge once a year and act accordingly if you notice chamber problems. And always look at your brass. It's probably the best indicator you have going for yourself.

Thanks for info - I have never had a problem with colt barrels.

I had the same results with Forster gages and the first Colt AR-15 I owned. It was a pencil barreled Sporter with triangle hand guards that sold for $235 new. The bolt closed on both "GO" and "NO-GO" gages. The rifle functioned perfectly. In my later Olympic and Kreiger barrels (CLE and Kreiger chambered), the bolt would not close on the "NO-GO". The old Colt chamber still closed easilly on the"NO-GO". I finally bought a Forster "FIELD" gage and the Colt then would not close the bolt.

I had a problem with a forster No-Go also and it was with a brand new RRA M4gery chrome lined barrel and a new RRA bolt. It closed, but tightly.  After a call into RRA made me realize that forsters are .223.  I checked it with my field 5.56 and everything checks OK.  You really can't play around with headspace.